1. Field of the Invention
The invention relates to a contact element having an outer conductor and a center conductor arranged within the outer conductor, which conductors are each intended to make contact with a component, and in particular a printed circuit board, at end-faces.
2. Description of Related Art
Contact elements may be used to connect (co-axial) conductors in cable form to the appropriate points of contact on a printed circuit board. Such contact elements may also be intended for the electrically conductive connection of two printed circuit boards.
If contact elements of this kind are used as part of a transmission line for radio-frequency signals, there are special requirements that have to be met by the contact made by the outer and center conductors with the points of contact on the printed circuit board.
The center conductor then regularly takes the form of a spring-loaded contact pin, also referred to as a “Pogo pin”. A spring-loaded contact pin of this kind comprises a sleeve, and a rod which has a contact-making head and of which a part is guided within the sleeve to be movable. A coil spring which is supported between the rod and the sleeve causes the rod to be spring-loaded to its extended position. The spring-loading causes the contact-making head of the rod always to be in secure contact with the point of contact on the printed circuit board and to be applied with an adequate pressure even when, due to tolerances, there are different distances between the spring-loaded contact pin and said point of contact. The contact-making head is regularly of a hemispherical form, which compensates for deviations by the spring-loaded contact pin, due to tolerances, from a perpendicular alignment with the point of contact, i.e., the area of the contact-making head which makes contact is always of substantially the same size.
The outer conductor, which regularly surrounds the center conductor concentrically, has an annular end-face which in many cases also serves as a contact-making surface. This is a disadvantage particularly when, due to tolerances, the outer conductor is not in exactly perpendicular alignment with the surface for contact on the printed circuit board. A lifting away of the contact-making surface on one side then results in contact with the point of contact still existing over only a comparatively small portion of the end-face of the outer conductor. “Uncontrolled” contact of this kind is undesirable particularly when the contact elements concerned are being used to transmit radio-frequency signals.